Known monitoring systems for measuring and control equipment allow for the system to enter a so-called secure state in response to a malfunction occurring. The secure state either causes the current operating state of the measuring and control equipment to change or prevents the operating state from being changed at a later time. One can then provide for, e.g. the measuring and control equipment, the system controlled by the measuring and control equipment, or the measuring and control equipment and the controlled system, being switched off in response to the occurrence of a malfunction.
A system for controlling and/or regulating an internal combustion engine is known from German Published patent Application No. 40 04 083. This includes several sensors, which generate signals that represent the operating parameters of the internal combustion engine. Malfunction detection is carried out, using these signals. The malfunction monitoring occurs within predefined sub-ranges having a lower sensitivity than outside of these predefined sub-ranges. If a malfunction is detected, then it can initially be checked if this can be attributed to impaired or incomplete signal transmission. The system is only switched off, when this is not the case. In this manner, the system is prevented from switching off in response to a malfunction of one of the sensors.
A disadvantage of the described system is that the system is immediately switched off in response to the occurrence of certain malfunctions. This indeed means that the safety of operation is high, but also that the availability is insufficient.